Honeywell Super Tradeline T874R User manual

Honeywell
T874R Thermostats and Q674L Subbases
Installation Instructions for the Trained Service Technician.
TRADELINE•
INSTALLATION INSTRUCTIONS
APPLICATION
The T874R Thermostat and Q674L Subbase provde 24 to 30 Vac control of 2-stage heatng and 1-stage cool-ng heat
pump systems wth manual changeover. Q674L Subbase provdes EM.HT.-HEAT-OFF-COOL system swtchng and
AUTO-ON fan swtchng. See Table 1 for specfc T874R/Q674L combnatons.
Table . Thermostat/Subbase Specifications.
Thermostat/
Subbase
Package
Thermostat/
Subbase
Model
Numbers LED Indication Changeover Comments See
Fig.
Y594R1243 T874R1152/
Q674L1207 AUX.HT.,
EM. HT. Manual Cool TRADELINE®; adjustable stage 2
heat antcpaton. Fxed antcpaton
n stage 1. Auto fan n EM.HT.
6
Y594R1300 T874R1475/
Q674L1520 AUX.HT.,
EM. HT.a Manual Heat
or Cool TRADELINE®; fxed heat
antcpaton. Auto fan n EM.HT. 7
Y594R1425 T874R1616/
Q674L1587 AUX.HT.,
EM. HT.,
CHECK
Manual Heat
or Cool SUPER TRADELINE®; fxed heat
antcpaton. Factory nstalled jumper
across W1 and Y1. Auto fan n
EM.HT.
8
Y594R1615 T874R1822/
Q674L1710 AUX.HT.,
EM. HT.,
CHECK
Manual Heat
or Cool TRADELINE®; fxed heat
antcpaton. Auto fan n EM.HT. 10
Y594R1664 T874R1871/
Q674L1736 EM. HT. Manual Cool TRADELINE®; exact replacement
for York model no. 2TH11702224. 9
Y594R1672 T874R1889/
Q674L1736 EM. HT. Manual Cool TRADELINE®; exact replacement
for York model nos. 2TH11702324
and 6TH11702224.
11
Y594R1698b T874R1905/
Q674L1777 EM. HT. Manual Cool TRADELINE®; exact replacement
for York model nos. 2TH11702324
and 6TH11702224. Includes
C815A1054 Outdoor Thermstor.
11
Y594R1706b T874R1913/
Q674L1777 EM. HT. Manual Cool TRADELINE®; exact replacement
for York model no. 2TH11702224. 9
Y594R1763 T874R1954/
Q674L1827 AUX.HT.,
EM. HT.a Manual Cool Requres C815A Outdoor Thermster
for outdoor reset. Fxed stage 1 heat
antcpaton. No heat antcpaton n
stage 2 heat. Auto fan n EM.HT.
Replaces Y594R1136.
5
Y594R1797 T874R1988/
Q674L1868 AUX.HT., EM.HT. Manual Heat
or Cool TRADELINE® 12
a EM.HT. LED also shows compressor malfuncton.
b Premer Whte® color.
®U.S. Registered Trademark
Copyright © 1997 Honeywe Inc. All Rights Reserved 69-0392-9

T874R THERMOSTATS AND Q674L SUBBASES
OPERATION
n a 2 -h e a t th e rm o sta t, th e tw o s ta g e s o f he a t make
s e q u e n tia lly a s th e te m p e ra tu re d ro ps. Make re fe rs to th e
m e rc u ry s w itc h in itia tin g a c a ll fo r h ea t o r cool.
T he re is a b o u t 1° F (0 .6 ° C) b e tw e en s ta g e s s o th e s e c
o nd s ta g e m a k e s o n ly w h e n th e firs t s ta g e ca n n o t h an dle
th e lo a d . T h e 1° F (0.6° C) is re fe rre d to a s th e interstage
differential
T he lig h t e m ittin g d io d e s (L E D ) o n the s u b b a se lig h t w h e n
so m e th in g s p e c ific h a p p e n s w ith in th e s ys te m . W h e n an
LE D lig hts, re fe r to th is list fo r the m ea nin g:
E M . H T.: E m e rg e n c y h ea t is o pe ra tin g. T h e c o m p re s 
s o r h as fa ile d , a n d th e h ea t p um p is n ot o pe ra tin g.
L E D lig hts w h e n s ys te m sw itc h is p la ce d in th e
E M .H T . p o sitio n b y th e h o m e o w n e r.
A U X .H T .: A u xilia ry h ea t is o p e ra tin g, w h ic h m e a n s the
w e a th e r is so c o ld th a t th e he a t p um p c an no t h an dle
th e lo ad.
C H E C K : S y s te m n e e d s to be c he ck ed . S e e h e a tin g
s y s-te m in s tru ctio n s fo r s p e cific m e an in g.
N T E : L E D s a re n o t fie ld re p la ce a ble o r a dd a b le .
®) RECYCLING NOTICE
T h is c o ntro l c o nta in s m e rcury in a s e a le d tube. D o no t
pla ce co ntro l in the tra sh a t the end o f its u se ful life.
If th is c o n tro l is re p la c in g a c o ntro l th a t c on ta in s
m e r-c u ry in a s e a le d tu be , d o notp la ce y o u r o ld
co ntro l in th e tra sh .
C o n ta ct y o ur lo cal w a s te m a n a g e m e n t a u th o rity fo r
in s tru c tio ns re ga rd in g re c y clin g a n d th e p ro pe r
d is po sa l of th is c o ntro l, o r o f a n o ld c o ntro l
co n ta in in g m e rc u ry in a s e a le d tub e .
INSTALLATION
When Installing this Product...
1. R e ad th e s e in s tru ctio n s c a re fu lly . F a ilu re to fo llo w
th e m c o u ld d am a g e th e p ro d u ct o r c a u s e a h az a rd 
o u s c o nd itio n.
2. C h e ck th e ra tin g s g iv e n in th e in s tru ctio n s a nd on
th e p ro du ct to m a k e su re th e pro d u ct is s u ita b le for
y o u r a p p lic a tio n.
3. In sta lle r m u st be a tra in ed , e x p e rie n ce d s erv ic e
te c h n ic ia n .
4 . A fte r in sta lla tio n is co m p le te , c h e c k o u t p ro du ct
o pe ra tio n a s p ro vid e d in th e se in stru ctio n s.
A CAUTION
1. D is co n ne ct p o w e r s u p p ly to p re v e n t e le ctrica l
s h o c k o r e q u ip m e n t d a m a ge .
2. T o p re v e n t in te rfe re n c e w ith th e th e rm o sta t
lin ka g e , k e ep w ire le n gth to a m in im u m and
ru n w ire s a s c lo se a s p os s ib le to th e s u bb ase .
3. P u s h e x c e s s w ire b a c k in to th e ho le a nd plug
h o le to pre ve n t d ra fts fro m a ffe ctin g th e rm o 
s ta t o pe ra tio n .
4. D o not o v ertig h te n th e rm o sta t c a p tiv e
m o u n tin g s cre w s b e c a u se d a m a g e to
s u b b as e th re a d s c a n result.
5. D o not s h o rt a c ro s s coil te rm in a ls o n h ea tin g
re la y o r g a s v a lv e . T h is ca n burn o u t th e
th e rm o s ta t h ea t a ntic ip a to r.
6. N e v e r in sta ll m o re th a n o ne w ire p e r te rm in al
u nle ss fa cto ry -s u p p lie d ju m p e r w ith sp ad e
te rm in a ls is u s e d .
IMPORTANT
Thermostats are calibrated at the factor using
subbase mounted at true level Inaccurate
subbase leveling causes the actual temperature
to deviate from the setpoint temperature.
Location
In sta ll th e th e rm o s ta t a b o u t 5 ft (1 .5 m ) a b o v e th e flo o r in
a n a re a w ith g o o d a ir c irc u la tio n a t a ve ra g e te m p e ra tu re .
D o n o t in sta ll th e th e rm o sta t w h e re it c a n be a ffe c te d by:
— d ra fts o r d e a d s p ots b e h in d d o o rs a nd in co rn ers .
— h o t o r c o ld a ir fro m du c ts .
— ra d ia nt he a t fro m su n o r a pp lia n ce s .
— c o n ce ale d p ip e s a n d ch im n eys .
— u n h e a te d (u n c oo le d) a re a s s u c h a s an o uts id e w a ll
b eh in d th e th erm o sta t.
Mounting The Subbase
T he th e rm o sta t s u b b a se c an be m o u n te d o n a v e rtic a l
o u tle t b ox , h oriz o n ta l o u tle t b o x o r d ire c tly on th e w a ll.
1. If y ou m u st m o u n t th e s u bb a s e o n a v e rtic a l o utle t
box, o rd e r H o ne y w e ll 1 93 12 1A A d a p te r A s s em b ly .
S e e Fig. 1. T h e a s s e m b ly in clu d e s a n a d a pte r ring,
tw o s cre w s a n d a c o ve r p la te to c o v e r m a rk s o n th e
w a ll. Insta ll th e rin g a nd c o ve r p la te on th e v e rtic a l
o u tle t b ox.
F o r a w a ll in sta lla tio n , h o ld s u b b a s e in p o sitio n a nd
m a rk h o le s fo r a n c h ors . S e e F ig. 2. b ta in w a ll
a n c h o rs lo c a lly. B e ca re fu l th a t th e w ire s d o n ot fall
b ac k in to th e w a ll o p en in g. S e t a s id e s u bb a se . D rill
tw o 3 /1 6 in. (5 m m ) h ole s a n d g e n tly ta p an ch o rs
in to the h ole s u n til flu sh w ith th e w a ll.
69-0392—9 2

B>E>
T874R THERMOSTATS AND Q674L SUBBASES
N T INCLUDED WITH UNIT.
ACCESS RY PARTS AVAILABLE (193121A).
Fig. . Installation of subbase on outlet box.
4. Secure the cover plate (f used) and subbase wth
the screws provded. Do not fully tghten the
subbase screws.
5. Level the subbase by usng a sprt level. Frmly
tghten subbase mountng screws. See Fg. 3. The
subbase mountng holes provde for mnor out-of
level adjustments.
IMPORTANT
An incorrectl leveled subbase causes the
temperature control to deviate from setpoint.
Wiring the Subbase
All wrng must comply wth local electrcal codes and
ordnances. Follow equpment manufacturer wrng
nstructons when avalable. To wre subbase, proceed as
follows:
1. Connect the system wres to the subbase. See Fg.
5-12. A letter code for dentfcaton s located near
each termnal. The termnal barrer permts straght
or conventonal wraparound wrng connecton. See
Fg. 4.
2. Frmly tghten each termnal screw.
3. Ft wres as close as possble to the subbase. Push
excess wre back nto the hole.
4. Plug the hole wth nonflammable nsulaton to
prevent drafts from affectng the thermostat.
THERM STAT THERM STAT
(Up T 12) M927
Fig. 3. Subbase components and leveling procedure.
Fig. 2. Installation of subbase on wall.
2. Run wres to the thermostat locaton.
3. Pull wres through the cover plate (f used) and sub
base cable openng. See Fg. 3.
IMPORTANT
Use 18 gauge, color-coded thermostat cable for
proper wiring.
F R STRAIGHT
INSERTI N- F R W RAPAR UND-
STRIP 5/16 IN. (8 MM) STRIP 7/16 IN. (11 MM)
-BARRIER -
<-SUBBASE TERMINAL SCREW
Fig. 4. Wiring connections.
369-0392—9

T874R THERMOSTATS AND Q674L SUBBASES
THERM STAT SUBBASE SYSTEM C MP NENTS
Fig. 5. Internal schematic and typical wiring diagram for Y594R 763 (T874R 954/Q674L 827). Replaces
GE AY28X078, AY28X 39; Trane Baystat 39, Baystat 239 and Baystat 240;
and Honeywell Y594R 36 Thermostats.
THERM STAT
_____ A ______
\ /■ SUBBASE % /■ SYSTEM C MP NENTS
______ A _______
(H T) L1 L2
Fig. 6. Internal schematic and typical wiring diagram for Y594R 243 (T874R 52/Q674L 207).
69-0392—9 4

T874R THERMOSTATS AND Q674L SUBBASES
THERM STAT SYSTEM C MP NENTS
L1 L2
(H T)
Fig. 7. Internal schematic and typical wiring diagram for Y594R 300 (T874R 475/Q674L 520); fixed anticipation.
SUBBASE
THERM STA.T SUBBASE SYSTEM C MP NENTS
------ A ---------------- . / -------------------------------------- A-------------------------------------------- . y ---------------- A ------------
Fig. 8. Internal schematic and typical wiring diagram for Y594R 425 (T874R 6 6/Q674L 587). SUPER
TRADELINE®; universal model for heat, cool, or first stage heating changeover systems.
CHECK LED has isolated terminals for use in all systems.
569-0392—9

T874R THERMOSTATS AND Q674L SUBBASES
SUBBASE
____A
____
SYSTEM C MP NENTS
_________ A_
L1 L2
(H T)
A "
C MPRESS R
C NTACT R
v P WER SUPPLY. PR VIDE DISC NNECT MEANS AND VERL AD PR TECTI N AS REQUIRED.
IHERM SIAI
____ A ____
Fig. 9. Internal schematic and typical wiring diagram for Y594R 664 (T874R 87 /Q674L 736) and Y594R 706
(T874R 9 3/Q674L 777). Exact replacement for York model no. 2TH 702224.
THERM STAT SUBBASE SYSTEM C MP NENTS
rAN / A
N /
AN
W3 RELAY
L1
(H T)
L2
Fig. 0. Internal schematic and typical wiring diagram for Y594R 6 5 (T874R 822/Q674L 7 0). TRADELINE;
intended for use in applications where W2 and E terminals are not jumpered.
69-0392—9 6

T874R THERMOSTATS AND Q674L SUBBASES
SUBBASE
___ A ____
SYSTEM C MP NENTS
_________ A _____________
L1 L2
(H T)
Fig. . Internal schematic and typical wiring diagram for Y594R 672 (T874R 889/Q674L 736) and Y594R 698
(T874R 905/Q674L 777). Exact replacement for York model nos. 2TH 702324 and 6TH 702224.
IH ERM SIAI
____ A ____
/■
THERM STAT
____ A _____
N /
SUBBASE
__ A____
SYSTEM C MP NENTS
\ / --------------------- /N -------------------------- ^L1
(H T)
L2
A
TERMINAL LABELED C/X N S ME M DELS.
W3 TERMINAL AVAILABLE N S ME M DELS NLY.
Fig. 2. Internal schematic and typical wiring diagram for Y594R 797 (T874R 988/Q674L 868).
769-0392—9

T874R THERMOSTATS AND Q674L SUBBASES
Mounting the Thermostat
1. Remove the thermostat cover by pullng the bottom
edge of the cover away from the base untl t snaps
free from the cover clp.
NOTE: The cover s hnged at the top and can be
removed by pullng out at the bottom.
2. Carefully remove and dscard polystyrene packng
nsert that protects the mercury swtches durng
shpment.
3. Turn over the thermostat base and note the sprng
fngers that engage the subbase contacts. Make
sure the sprng fngers are notbent flat, preventng
proper electrcal contact wth the subbase.
4. Note the two tabs on the top nsde edge of the
thermostat base. The tabs ft nto correspondng
slots on the top of the subbase. Mount the thermo
stat on the subbase.
5. Algn the two captve mountng screws n the
thermostat base wth the posts on the subbase. See
Fg. 13. Tghten both screws. D o n o t overtighten
screw sor damage to subbase posts can result.
6. Hang the upper edge of the thermostat cover on top
of the thermostat base and swng cover downward
untl t engages wth the cover clp.
Fig. 3. Mounting thermostat on subbase.
SETTINGS
A CAUTION
On systems usng a gas valve, never apply a
jumper across the valve col termnals, even
temporarly. Ths can burn out the thermostat heat
antcpator(s).
eat Anticipator Setting
(2nd Stage Y594R1243)
Set the heat antcpator scale to match the prmary control
current draw. When usng a T874 Thermostat wth two
stages of heatng, set the heat antcpator to match the
respectve prmary control current draw. If the prmary
control nameplate has no ratng or f further adjustment s
necessary, use the followng procedure to determne the
current draw. Measure the current draw wth the thermo
stat removed and the power on.
1. Connect an ac ammeter of approprate range
between the heatng termnals of the subbase:
Stage 2: between W2 and R.
2. Move the system swtch to HEAT.
3. After one mnute, read the ammeter and record the
readng:
Stage 2: ______________ amperes.
4. After mountng the thermostat, set the adjustable
heat antcpator to match the respectve readng
measured n step 3.
If equpment cycles too fast, set the antcpator to a hgher
current ratng, not more than one-half dvson at a tme,
and recheck cycle rate. Most conventonal 2-stage heatng
equpment s desgned to operate at 3 cycles per hour per
stage. See Fg. 14.
Most heat pump systems should cycle 2-1/2 to 3 tmes
per hour.
Fig. 4. Adjustable heat anticipator scale.
Temperature Setting
Move the setpont lever to the desred comfort poston.
One lever controls both heatng and coolng.
Subbase Setting
System swtchng postons control thermostat operaton as
follows:
OFF: Heatng and coolng systems are off. If the fan
swtch s at the AUTO poston, the coolng fan s
also off.
HEAT: Heatng system s controlled by the thermostat.
Coolng system s off.
COOL: Coolng system s controlled by the thermostat.
Heatng system s off.
EM.HT.: Emergency heat relay s energzed on call for
heat. Coolng system s off. Compressor s de
energzed.
Fan swtchng postons control fan operaton as follows:
ON: Fan operates contnuously.
AUTO: Fan operates as controlled by the thermostat.
To swtch postons, use thumb and ndex fnger to slde
lever to desred poston. Stop swtch lever n detent
drectly over the desred functon ndcator mark for proper
crcut operaton.
69-0392—9 8

T874R THERMOSTATS AND Q674L SUBBASES
C ECKOUT
eating
Move the system swtch on the Q674 Subbase to HEAT.
Move the setpont lever on the T874 Thermostat about
10° F (6° C) above room temperature. Both stages of
heatng and the fan should start. Move the setpont lever
about 10° F (6° C) below room temperature. Heatng and
fan should shut off.
NOTE: To prevent compressor short cyclng, some
manufacturer equpment ncludes a mnmum-off
tmer to provde a fve-mnute tme delay before
turnng on the compressor after the thermostat
last turned off the compressor, or after the
system frst receved power. Ths delay protects
the compressor.
Cooling
A CAUTION
Do not operate coolng f the outdoor temperature
s below 50° F (10° C). Refer to manufacturer
recommendatons.
Move the system swtch on the Q674 Subbase to COOL.
Move the setpont lever on the T874 Thermostat about
10° F (6° C) below room temperature. Coolng and fan
should start (see NOTE above). Move the setpont lever
about 10° F (6° C) above room temperature. Coolng and
fan should stop.
Emergency eat
Move the system swtch to EM.HT. The EM.HT. LED
should come on. Move the setpont lever about 10° F
(6° C) above room temperature. The electrc strp heater(s)
should come on. Move the setpont lever about 10° F
(6° C) below room temperature. The electrc strp heater
should de-energze. The EM.HT. LED remans on untl
system swtch s moved to another poston.
Fan
Move the subbase system swtch to OFF and the fan
swtch to ON. The fan should run contnuously. When the
fan swtch s n the AUTO poston, fan operaton s con
trolled by the heatng or coolng system.
CALIBRATION
Thermostat
T874 Thermostats are accurately calbrated at the factory.
There is no provision fo r fie ld calibration.
Thermometer
The thermometer n the thermostat has been accurately
calbrated at the factory. The thermometer should need
adjustment only f t was dropped or shfted due to
mshandlng.
If the setpont lever and the thermometer readng do not
agree:
1. Remove the thermostat cover by pullng out from the
bottom of cover untl t clears the mountng slots.
2. Set the thermostat cover on a table near an
accurate thermometer.
3. Allow 10 or 15 mnutes for cover thermometer to
sense area temperature; compare the readngs. Be
careful not to touch thermometer or breathe on t.
4. If the readngs are the same, replace cover and put
the system nto operaton.
5. If the readngs are dfferent, nsert a small screw
drver nto the thermometer and turn t untl the
thermometers have the same readng. See Fg. 15.
6. Replace thermostat cover and put the system nto
operaton.
NOTE: Radant heat from hands offsets the thermometer
readng. After makng each adjustment, wat 10
or 15 mnutes for the thermometer to stablze
before comparng.
969-0392—9

69-0392—9 10

11 69-0392—9

Automation and Contro So utions
Honeywe Internationa Inc. Honeywe Limited—Honeywe Limitée
1985 Doug as Drive North 35 Dynamic Drive
Go den Va ey, MN 55422 Scarborough, Ontario M1V 4Z9
Honeywell
69-0392—9 G.H. Rev. 10-97
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